Abnormal haemodynamic response to exercise in heart failure with preserved ejection fraction

Area of Science:

• Cardiology
• Exercise Physiology
• Metabolic Research

Background:

• Patients with heart failure with preserved ejection fraction (HFpEF) exhibit reduced peak oxygen uptake (VO(2)), suggesting compromised cardiac reserve.
• Assessing the hemodynamic response to exercise is crucial for understanding functional limitations in HFpEF.

Purpose of the Study:

• To investigate the hemodynamic response to exercise in patients with HFpEF.
• To determine if cardiac reserve is impaired in HFpEF patients.

Main Methods:

• Compared exercise hemodynamics (cardiac output, VO(2)) in 11 HFpEF patients and 13 healthy controls.
• Measured cardiac output (Q(c)) using acetylene rebreathing during graded exercise.
• Determined peak oxygen uptake (VO(2)) using Douglas bags.

Main Results:

• HFpEF patients had significantly lower peak VO(2) compared to controls (13.7 ± 3.4 vs. 21.6 ± 3.6 mL/kg/min).
• Peak cardiac power output and stroke work were not significantly different between groups, indicating preserved cardiac reserve.
• The ratio of change in cardiac output to change in VO(2) (ΔQ(c)/ΔVO(2)) was significantly higher in HFpEF patients (11.2 ± 3.6 vs. 8.3 ± 1.5).

Conclusions:

• Cardiac reserve is not significantly impaired in well-compensated HFpEF outpatients.
• The abnormal exercise response in HFpEF, characterized by reduced peak VO(2) and an increased ΔQ(c)/ΔVO(2) slope, suggests impaired skeletal muscle oxidative metabolism.
• This skeletal muscle impairment may contribute to reduced functional capacity through premature fatigue and exaggerated metabolic signals for cardiac output, potentially stressing a diastolic-impaired left ventricle.